Contribution of regional aerosol nucleation to low-level CCN in an Amazonian deep convective environment: results from a regionally nested global model
<p>Global model studies and observations have shown that downward transport of aerosol nucleated in the free troposphere is a major source of cloud condensation nuclei (CCN) to the global boundary layer. In Amazonia, observations show that this downward transport can occur during strong convec...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/4431/2023/acp-23-4431-2023.pdf |
| _version_ | 1827967071840894976 |
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| author | X. Wang H. Gordon D. P. Grosvenor M. O. Andreae K. S. Carslaw |
| author_facet | X. Wang H. Gordon D. P. Grosvenor M. O. Andreae K. S. Carslaw |
| author_sort | X. Wang |
| collection | DOAJ |
| description | <p>Global model studies and observations have shown that downward transport of aerosol nucleated in the free troposphere is a major source of cloud condensation nuclei (CCN) to the global boundary layer. In Amazonia, observations show that this downward transport can occur during strong convective activity. However, it is not clear from these studies over what spatial scale this cycle of aerosol formation and downward supply of CCN is occurring. Here, we aim to quantify the extent to which the supply of aerosol to the Amazonian boundary layer is generated from nucleation within a 1000 km regional domain or from aerosol produced further afield and the effectiveness of the transport by deep convection. We run the atmosphere-only configuration of the HadGEM3 climate model incorporating a 440 km <span class="inline-formula">×</span> 1080 km regional domain over Amazonia with 4 km resolution. Simulations were performed over several diurnal cycles of convection. Below 2 km altitude in the regional domain, our results show that new particle formation within the regional domain accounts for only between 0.2 % and 3.4 % of all Aitken and accumulation mode aerosol particles, whereas nucleation that occurred outside the domain (in the global model) accounts for between 58 % and 81 %. The remaining aerosol is primary in origin. Above 10 km, the regional-domain nucleation accounts for up to 66 % of Aitken and accumulation mode aerosol, but over several days very few of these particles nucleated above 10 km in the regional domain are transported into the boundary layer within the 1000 km region, and in fact very little air is mixed that far down. Rather, particles transported downwards into the boundary layer originated from outside the regional domain and entered the domain at lower altitudes. Our model results show that CCN entering the Amazonian boundary layer are transported downwards gradually over multiple convective cycles on scales much larger than 1000 km. Therefore, on a 1000 km scale in the model (approximately one-third the size of Amazonia), trace gas emission, new particle formation, transport and CCN production do not form a “closed loop” regulated by the biosphere. Rather, on this scale, long-range transport of aerosol is a much more important factor controlling CCN in the boundary layer.</p> |
| first_indexed | 2024-04-09T17:59:36Z |
| format | Article |
| id | doaj.art-f38bea57e826497d9a771cb592e54346 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-09T17:59:36Z |
| publishDate | 2023-04-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-f38bea57e826497d9a771cb592e543462023-04-14T09:46:08ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242023-04-01234431446110.5194/acp-23-4431-2023Contribution of regional aerosol nucleation to low-level CCN in an Amazonian deep convective environment: results from a regionally nested global modelX. Wang0H. Gordon1D. P. Grosvenor2M. O. Andreae3K. S. Carslaw4School of Earth and Environment, University of Leeds, LS2 9JT, Leeds, UKDepartment of Chemical Engineering and Center for Atmospheric Particle Studies, Carnegie Mellon University, Pittsburgh, PA 15213, USASchool of Earth and Environment, University of Leeds, LS2 9JT, Leeds, UKBiogeochemistry, Multiphase Chemistry, and Particle Chemistry Departments, Max Planck Institute for Chemistry, Mainz, GermanySchool of Earth and Environment, University of Leeds, LS2 9JT, Leeds, UK<p>Global model studies and observations have shown that downward transport of aerosol nucleated in the free troposphere is a major source of cloud condensation nuclei (CCN) to the global boundary layer. In Amazonia, observations show that this downward transport can occur during strong convective activity. However, it is not clear from these studies over what spatial scale this cycle of aerosol formation and downward supply of CCN is occurring. Here, we aim to quantify the extent to which the supply of aerosol to the Amazonian boundary layer is generated from nucleation within a 1000 km regional domain or from aerosol produced further afield and the effectiveness of the transport by deep convection. We run the atmosphere-only configuration of the HadGEM3 climate model incorporating a 440 km <span class="inline-formula">×</span> 1080 km regional domain over Amazonia with 4 km resolution. Simulations were performed over several diurnal cycles of convection. Below 2 km altitude in the regional domain, our results show that new particle formation within the regional domain accounts for only between 0.2 % and 3.4 % of all Aitken and accumulation mode aerosol particles, whereas nucleation that occurred outside the domain (in the global model) accounts for between 58 % and 81 %. The remaining aerosol is primary in origin. Above 10 km, the regional-domain nucleation accounts for up to 66 % of Aitken and accumulation mode aerosol, but over several days very few of these particles nucleated above 10 km in the regional domain are transported into the boundary layer within the 1000 km region, and in fact very little air is mixed that far down. Rather, particles transported downwards into the boundary layer originated from outside the regional domain and entered the domain at lower altitudes. Our model results show that CCN entering the Amazonian boundary layer are transported downwards gradually over multiple convective cycles on scales much larger than 1000 km. Therefore, on a 1000 km scale in the model (approximately one-third the size of Amazonia), trace gas emission, new particle formation, transport and CCN production do not form a “closed loop” regulated by the biosphere. Rather, on this scale, long-range transport of aerosol is a much more important factor controlling CCN in the boundary layer.</p>https://acp.copernicus.org/articles/23/4431/2023/acp-23-4431-2023.pdf |
| spellingShingle | X. Wang H. Gordon D. P. Grosvenor M. O. Andreae K. S. Carslaw Contribution of regional aerosol nucleation to low-level CCN in an Amazonian deep convective environment: results from a regionally nested global model Atmospheric Chemistry and Physics |
| title | Contribution of regional aerosol nucleation to low-level CCN in an Amazonian deep convective environment: results from a regionally nested global model |
| title_full | Contribution of regional aerosol nucleation to low-level CCN in an Amazonian deep convective environment: results from a regionally nested global model |
| title_fullStr | Contribution of regional aerosol nucleation to low-level CCN in an Amazonian deep convective environment: results from a regionally nested global model |
| title_full_unstemmed | Contribution of regional aerosol nucleation to low-level CCN in an Amazonian deep convective environment: results from a regionally nested global model |
| title_short | Contribution of regional aerosol nucleation to low-level CCN in an Amazonian deep convective environment: results from a regionally nested global model |
| title_sort | contribution of regional aerosol nucleation to low level ccn in an amazonian deep convective environment results from a regionally nested global model |
| url | https://acp.copernicus.org/articles/23/4431/2023/acp-23-4431-2023.pdf |
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